Extracranial Hypoglossal Schwannoma: Case Report and Literature Review

Abstract

Background: Schwannomas are solitary neurogenic tumors originating from the myelin sheath of peripheral nerves. Extracranial hypoglossal schwannomas comprise <5% of all head and neck schwannomas and can mimic submandibular salivary gland tumors.

Case report: We report the diagnostic imaging, surgical treatment, and histopathological findings of a rare case of extracranial schwannoma of the hypoglossal nerve in a 73-year-old female, presented with an asymptomatic swelling in the left submandibular region that had been persisted for approximately three years.

Conclusion: Accurate diagnosis of this rare clinical entity requires comprehensive diagnostics. The optimal therapeutic strategy is nerve-sparing surgical excision, although it can be challenging.

Keywords: Extracranial schwannoma; hypoglossal nerve; submandibular region.

Figure 1. Preoperative view of the left lateral neck: Well-defined and slightly mobile lesion of hard elastic consistency in the left submandibular region.

Figure 2. Axial and coronal views of the contrast-enhanced computed tomography (CT) scan of the head and neck. A) Orange arrow demonstrates a well-defined hypodense lesion with inhomogeneous density in the left submandibular region, approximately to the mandibular angle. B) Arrows demonstrate enhancement of intratumoral blood vessels. C: Coronal view of the contrast-enhanced CT scan of the head and neck demonstrates the neoplasm located lateral to the genioglossus and hypoglossus muscles. The submandibular gland appears displaced inferiorly.

Figure 3. Histopathological examination under microscope. A) Encapsulated tumour showing alternate hypercellular (Antoni A) and hypocellular (Antoni B) areas (H&E, ×100). B) hypercellular areas showing bland spindle cells with evidence of wavy nucleus and nuclear palisading (H&E, ×200). Antoni type A is composed of spindle shaped Schwann cells with elongated nuclei arranged in streams and nuclear palisades known as Verocay bodies. Antoni type B consists of less spindle cells and has a myxoid background. C) Immunohistochemistry: neoplastic cells are diffusely and strongly stained for S-100 and SOX10. SOX10: SRY-related HMG-box 10.